﻿/* ==============================================================================
*
*   Copyright (c) 2010, Pierre Favier
*   All rights reserved.
*
*   NTasking is free software: you can redistribute it and/or modify it
*   under the terms of the GNU General Public License as published by the
*   Free Software Foundation.
*
*   Redistribution and use in source and binary forms, with or without
*   modification, are permitted provided that the following conditions
*   are met:
*
*   -   Redistributions of source code must retain the above copyright notice,
*       this list of conditions and the following disclaimer.
*
*   -   Redistributions in binary form must reproduce the above
*       copyright notice, this list of conditions and the following
*       disclaimer in the documentation and/or other materials
*       provided with the distribution.
*
*   THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
*   WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
*   OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
*   DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
*   BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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*   TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
*   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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*   THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* ============================================================================== */

using System;
using System.Collections.Generic;
using NTasking;

namespace NTaskingQuickStart.Printing
{

    internal class JobSpooler : Protected
    {

        private readonly List<PrintJob> _printJobs;
        private readonly Dictionary<Guid, PrintStatus> _printResults;
        private bool _shutdown;
        

        [Entry]
        internal Func<string, PrintStatus> Print { get; private set; }
        
        [Entry]
        private FuncFamily<Guid, PrintStatus> WaitForResult { get; set; }
        
        [Entry]
        internal Func<PrintJob> NextJob { get; private set; }
        
        [ReadWriteOperation]
        internal Action<Guid, PrintStatus> DonePrinting { get; private set; }
        
        [ReadWriteOperation]
        internal Action Shutdown { get; private set; }
        
        
        internal JobSpooler()
        {
            _printJobs = new List<PrintJob>();
            _printResults = new Dictionary<Guid, PrintStatus>();
            
            Entry(Print,
                When: () => true,
            Is: (string file) =>
            {
                if (_shutdown)
                    return PrintStatus.Shutdown;

                Guid jobId = Guid.NewGuid();
                _printJobs.Add(new PrintJob(jobId, file));
                Requeue(WaitForResult[jobId]);

                // Will never get here because of the requeue statement above
                // but to keep compiler happy we need a return statement here
                return PrintStatus.Failure;
            });
            
            
            Entry(WaitForResult,
                When: jobId => _printResults.ContainsKey(jobId),
            Is: (Guid jobId) =>
            {
                PrintStatus result = _printResults[jobId];
                _printResults.Remove(jobId);
                return result;
            });
            
            
            Entry(NextJob,
                When: () => _printJobs.Count > 0 || _shutdown,
            Is: () =>
            {
                if (_printJobs.Count > 0)
                {
                    PrintJob job = _printJobs[0];
                    _printJobs.RemoveAt(0);
                    return job;
                }

                return null;
            });
            
            
            ReadWriteOperation(DonePrinting, Is: (Guid jobId, PrintStatus result) =>
            {
                _printResults[jobId] = result;
            });


            ReadWriteOperation(Shutdown, Is: () =>
            {
                _shutdown = true;
            });
        }
        
    }

}